Allium genus plants include garlic, elephant garlic, scallion, onion, spring onion, green onion, leek, chives, and the like, and all have specific flavor. Since the ancient days, they have been cultivated all over the world as vegetables or medicinal plants. Among others, garlic is a perennial plant which is grown in Chine, Korea, Japan and many other countries. It is generally known as a tonic or restorative drug and has long been used as stomachic, diuretic, expectorant, intestinal controlling, bactericidal, and anthelmintic agents. There are many reports on characteristic sulfur components of garlic such as allicin, diallylsulfide, S-allylcysteine, ajoene, etc. Recent researches on the pharmaceutical action of these components are reported in the literature and patents, for example, Lancet, 1, 8212, 150-151 (1982), and Japanese Patent Application Kokai Nos. 42967/1980, 5203/1981, 209218/1982, 140526/1986. Among others, S-allylcysteine has been reported as effective in controlling hepatopathy (Hiroshima, Journal of Medical Sciences, 34, 3, 303-309 (1985)), in protecting against radiation (Z. Naturforsch, 35 c, 726 (1980)), and in controlling oncogenesis (Proceedings of the American Association for Cancer Research, 30, 181 (1989)). Practical application of S-allylcysteine is expected. Also, elephant garlic is grown in Japan, U.S., and other countries and widely used like garlic. It was recently reported that elephant garlic contains steroid saponins having antibacterial action (see Chem. Pharm. Bull., 36, 3480-3486 (1988) and Japanese Patent Application Kokai No. 224396/1989). Regarding the treatments, typically deodorizing treatment of garlic and analogues, a number of reports have been available.
However, in the production of a composition rich in a selected component derived from an Allium genus plant, few methods are known except for ajoene derived from garlic (see Japanese Patent Application Kokai No. 129224/1987). No method for producing an S-allylcysteine rich composition is known.